Recent Topics
Pulling axle question
by supton - 02/25/20 07:50 AM
Sams Club gas
by dbvettez061 - 02/25/20 07:44 AM
2019 Ram Battery Issue
by NYEngineer - 02/25/20 06:00 AM
belt squeaking suddenly
by dogememe - 02/24/20 11:45 PM
Is Mobil 1 advanced synthetic a full synthetic?
by apollo18 - 02/24/20 11:08 PM
what stocks to buy?
by daves66nova - 02/24/20 08:55 PM
I thought Windows 7 would be insecure now?
by atikovi - 02/24/20 08:48 PM
When to replace struts
by ram_man - 02/24/20 08:40 PM
Fluid Film + Cayenne Pepper
by pitzel - 02/24/20 05:22 PM
Ford Focus RS Oil Advice!
by fastsvo - 02/24/20 04:23 PM
Cleanest wheels on same axle or same side of car?
by atikovi - 02/24/20 04:13 PM
Mixing 2 stroke oils
by Hirev - 02/24/20 03:57 PM
Insa Turbo Ecosaver Plus
by faramir9 - 02/24/20 03:45 PM
Repair Rusted Rocker Panels Without Welding
by Fitz98 - 02/24/20 03:33 PM
Stalwart tools
by P10crew - 02/24/20 03:32 PM
VOA Eneos Racing Street 0w-50
by zip15 - 02/24/20 03:09 PM
What is your favorite Candy Bar?
by ZZman - 02/24/20 02:27 PM
Help me understand
by 1978elcamino - 02/24/20 02:25 PM
Newest Members
EarlT500, Newbie111, Boris_Be, NHR, zip15
70798 Registered Users
Who's Online Now
112 registered members (apollo18, 28oz, 2013ecof150, 2012AccentSE, alchargo, Anduril, 5 invisible), 2,298 guests, and 19 spiders.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums67
Topics301,901
Posts5,205,040
Members70,798
Most Online4,538
Jan 20th, 2020
Donate to BITOG
Print Thread
Hop To
Page 1 of 2 1 2
747 goes supersonic* #5345371 02/09/20 02:44 PM
Joined: Oct 2013
Posts: 1,533
DeepFriar Offline OP
OP Offline
Joined: Oct 2013
Posts: 1,533
Well sort of. Would you believe an average of 801 mph between New York and London? I should live so long as to see a tailwind of 260! We'll miss her when she's gone, monumental achievement that she was.

https://jalopnik.com/with-help-from-a-storm-a-british-airways-747-just-brok-1841557907

Re: 747 goes supersonic* [Re: DeepFriar] #5345378 02/09/20 02:54 PM
Joined: May 2012
Posts: 3,730
SubieRubyRoo Offline
Offline
Joined: May 2012
Posts: 3,730
It's a darn shame that profreading(sic) is a lost art LOL


De omnibus dubitandum.
Re: 747 goes supersonic* [Re: DeepFriar] #5345411 02/09/20 03:33 PM
Joined: Mar 2017
Posts: 12,580
PimTac Offline
Offline
Joined: Mar 2017
Posts: 12,580
I guess the meaning of supersonic has changed since I went to school.


2017 Mazda CX5
Valvoline Advanced Synthetic 0w20
Roki OEM filter.
Re: 747 goes supersonic* [Re: PimTac] #5345464 02/09/20 04:56 PM
Joined: Aug 2013
Posts: 728
T
tcp71 Offline
Offline
T
Joined: Aug 2013
Posts: 728
801mph is over the supersonic speed of 768mph. That plane would beat sound from New York to London = “supersonic”. Works for me.
[Linked Image]

Last edited by tcp71; 02/09/20 04:57 PM.

2016 F150 Eco: Edge 0w40
2005 Sienna 3.3: NAPA 5w30 syn. (varies)
Re: 747 goes supersonic* [Re: DeepFriar] #5345493 02/09/20 05:41 PM
Joined: Dec 2002
Posts: 43,589
J
JHZR2 Offline
Global Moderator
Offline
Global Moderator
J
Joined: Dec 2002
Posts: 43,589
I was going to post on this too.

Are commercial jetliners “designed” (at least built with sufficient margin and safety factors) to go over 800mph?

I thought special considerations had to be made even for surface paint temperatures?

I’m not calling it supersonic because it’s awful high and awful cold up there, and those conditions change the speed of sound IIRC....

Re: 747 goes supersonic* [Re: DeepFriar] #5345497 02/09/20 05:44 PM
Joined: May 2010
Posts: 11,079
S
spasm3 Online Happy
Online Happy
S
Joined: May 2010
Posts: 11,079
Originally Posted by JHZR2
I’m not calling it supersonic because it’s awful high and awful cold up there, and those conditions change the speed of sound IIRC....

Also, is it really supersonic with a tailwind of 260? Relative to ground i guess its over 800. Relativity wise, is the air-frame really seeing 800mph?

Calling Astro!


13 elantra 81k 5w30 synpwr
03 chevy avalanche 83k synpwr 5w30
17 mazda cx-5 17000 miles synpwr 5w30
Re: 747 goes supersonic* [Re: DeepFriar] #5345498 02/09/20 05:45 PM
Joined: Oct 2014
Posts: 14,495
C
CT8 Offline
Offline
C
Joined: Oct 2014
Posts: 14,495
Jetstream 260 mph plus the plane speed is not actually the speed of sound ,


2015 F150 2.7
2018 F350 6.2
Re: 747 goes supersonic* [Re: DeepFriar] #5345514 02/09/20 06:10 PM
Joined: Mar 2017
Posts: 12,580
PimTac Offline
Offline
Joined: Mar 2017
Posts: 12,580
The articles say subsonic.

This is Jalopnik. 🧂🧂🧂


2017 Mazda CX5
Valvoline Advanced Synthetic 0w20
Roki OEM filter.
Re: 747 goes supersonic* [Re: PimTac] #5345526 02/09/20 06:22 PM
Joined: Jul 2014
Posts: 1,298
Number_35 Offline
Offline
Joined: Jul 2014
Posts: 1,298
Originally Posted by PimTac
I guess the meaning of supersonic has changed since I went to school.
Agreed, I think that supersonic speed is literally that at which the speed of sound is exceeded, and is thus relative to the surrounding air. The jet stream wind speed would have to be subtracted from the ground speed to give the actual air speed of the aircraft.

As well, the speed of sound (Mach 1) is c. 760 mph @ STP (standard temperature and pressure, 20 C @ sea level) but decreases with altitude, as atmospheric pressure drops. As atmospheric pressure drops, the air becomes less dense, and sound travels more slowly. This chart helps:

https://www.fighter-planes.com/jetmach1.htm

Per the chart, the speed of sound is about 660 mph at typical airliner altitudes. The aircraft under consideration is said to have hit a maximum ground speed of 825 mph, but if we subtract the 260 mph tailwinds, we're left with a maximum airspeed of 565 mph, well below supersonic (660 mph) at that altitude.

To put it another way, if you could somehow have projected a loud sound from the aircraft, its waves would have traveled in front of (that is, faster than) the aircraft, not behind the aircraft.

Re: 747 goes supersonic* [Re: DeepFriar] #5345530 02/09/20 06:27 PM
Joined: Apr 2017
Posts: 3,234
H
hallstevenson Online Content
Online Content
H
Joined: Apr 2017
Posts: 3,234
Did anyone read the article ?

Originally Posted by article
...it wouldn’t have broken the sound barrier as the differential between the speed of the plane and the air moving around it was to low.

Re: 747 goes supersonic* [Re: SubieRubyRoo] #5345538 02/09/20 06:38 PM
Joined: Jan 2011
Posts: 4,592
AZjeff Offline
Offline
Joined: Jan 2011
Posts: 4,592
Originally Posted by SubieRubyRoo
It's a darn shame that profreading(sic) is a lost art LOL


You mean the Subsonic in the headline? Maybe it's correct as the jet didn't technically go supersonic but averaged 801 mph?



14 RAV4 2.5 5W-20 PP
18 Nissan Titan 5.6 DI, 0W-20 QSUD

The most important thing to do in your life is to not interfere with someone else's life. - Frank Zappa

Re: 747 goes supersonic* [Re: hallstevenson] #5345561 02/09/20 07:12 PM
Joined: Dec 2002
Posts: 43,589
J
JHZR2 Offline
Global Moderator
Offline
Global Moderator
J
Joined: Dec 2002
Posts: 43,589
Originally Posted by hallstevenson
Did anyone read the article ?

Originally Posted by article
...it wouldn’t have broken the sound barrier as the differential between the speed of the plane and the air moving around it was to low.


I saw a different article. But that’s why I didn’t claim it to be supersonic.

Still, the ground speed, tailwind or not, seems to me to be impressive. Not that I know much about flying... but I know if I go much over 30 on a bicycle, down a hill and in a tailwind, it’s not the most comforting feeling... regardless of the reason the speed is achieved... thus my curiosity on what the design speed is.

Re: 747 goes supersonic* [Re: DeepFriar] #5345574 02/09/20 07:23 PM
Joined: May 2010
Posts: 11,079
S
spasm3 Online Happy
Online Happy
S
Joined: May 2010
Posts: 11,079
Try that on the next traffic stop!! " You were doing 20 over" ; " But i had a 12mph tail wind!"


13 elantra 81k 5w30 synpwr
03 chevy avalanche 83k synpwr 5w30
17 mazda cx-5 17000 miles synpwr 5w30
Re: 747 goes supersonic* [Re: DeepFriar] #5345640 02/09/20 08:39 PM
Joined: Feb 2019
Posts: 242
V
vw7674 Offline
Offline
V
Joined: Feb 2019
Posts: 242
Right time,right route,right conditions,even a four engine freighter/transport can do concorde like cross-Atlantic travel times.
The relative wind kept the loads to subsonic levels.

Re: 747 goes supersonic* [Re: DeepFriar] #5345653 02/09/20 08:47 PM
Joined: Oct 2013
Posts: 1,533
DeepFriar Offline OP
OP Offline
Joined: Oct 2013
Posts: 1,533
Gentlemen this item was firmly tongue in cheek hence the asterisk. Supersonic in this case is just numerical. The 747 was no more supersonic than when there is no tailwind. Sub five hour flight from New York to London is still remarkable even for the extreme swept wing wonder from Everett and is the real *story* here.

Page 1 of 2 1 2
Previous Thread
Index
Next Thread

BOB IS THE OIL GUY® Powered by UBB.threads™